Mortar barges

Kazziga

Corporal
Joined
Mar 22, 2011
Location
Gliwice, Poland
Almost 10 year ago I built a little paper model of a Union mortar boat. The model was a free download from "Paper Shipwright": http://www.papershipwright.co.uk/mortar-barge-no-10/
As it often happens, we do things first and think about them later and such was the case with my model.
Before I built it, I had seen illustrations and photos of similar craft and while the shape of the shield (casemate sounds too serious here, at least for me) was ok, the shape of the hull was not. Since I wanted to build the kit, I didn't care much about it then.

Check these illustrations and photos:
http://civilwarnavy150.blogspot.com/2012/04/unfavorable-mortar-boats.html
http://civilwarhorror.blogspot.com/2013/06/civil-war-photo-friday-union-mortar-boat.html
http://www.valdressamband.org/images/civilwar/C4.jpg
http://www.sonofthesouth.net/leefoundation/civil-war/1861/december/ft-pickens-bombardment.htm (bottom image)
http://www.flickr.com/photos/whsimages/6209003302/ (hull under construction)
http://civilwardailygazette.com/wp-content/uploads/2011/09/jan21mortarboat1.jpg

As you can see, the photos show the hull form as rectangular, while the model(s) often have triangular ends:
http://www.flagshipmodels.com/zencart/index.php?main_page=product_info&cPath=7&products_id=119

I hope someone here is interested in these boats and will be able to shed some light on the subject.
 
Kaz, I do not have specific supportable pics or data, but my impression over the years has been that the hull has the triangular end, in effect, continuing the form of the shield/casemate. However, the deck is rectabgular, as reflected in the photos. Simplot's sketch of the construction would show the build before the deck has been added.
 
Neil, I have always thought that hulls of mortar boats were based on standard river barges and those were mainly rectangular in shape.
 
I have a photo of one somewhere, which I came across just because mortar schooners became fascinating. I just could not understand how something floating could withstand having a blast that large take place from a deck- these barges, gee whiz. It just seems like the firing of one would have to send a barge skipping across the water like a tobaggan on snow. I realize I know little about artillery- but the blast has to go somewhere. My husband still won't let me shoot one of his larger caliber pistols due to this er, problem. We still disagree on how hilarious a bleeding forehead might be. Ok, it's pretty funny.

Anyway, one of these guns, you see photos of what has to be built on land to house the thing. I'm just baffled as to how on earth they engineered a floating bed for one. Kind of amazing, no?
 
They may have been based on barges, but they were purpose-built, and built to withstand the force; they actually had some draft. For example, Meagher's plan, drawn in 1994, shows a draft of 12 1/2' (he also describes the length at 45', however). I thought pointed-ends made sense because of the need to maneuver in the current (which they did by ropes attached to land, as illustrated in some of the pictures).
 
I don't have any special knowledge about it, but I have always assumed that the under-water configuration was a simple scow shape with perpendicular sides. Nothing fancy.
 
Wouldn't a 12 1/2' draft be rather deep for where they were using these craft?
 
It sure seems deep to me, too, especially for river-work. Perhaps someone with some technical knowledge could opine about what support a 13" mortar would actually need.
 
2 1/2' maybe? That said with the mortar itself weighing 17,000# +/- and each round weighing 225#, I don't know if the 2 1/2' draft is reasonable-maybe we have a marine engineer or a naval architect out there that can tell us.
 
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There's a discussion in the CWReenactors Forum:
http://www.cwreenactors.com/forum/showthread.php?11154-Mortar-Rafts
See also 'Mortar Boats' at:
http://www.cityofart.net/bship/frameset5.htm
Google Images has a lot of pics for "mortar barge", but few are really clear. Some appear to be little more than rafts with rather crude casemates. Some clearly pointed, others square, a few with tapered/blunted ends (can't remember the name for that 'trapezoidal' shape).
Also the bottom image here:
http://www.sonofthesouth.net/leefoundation/civil-war/1861/december/ft-pickens-bombardment.htm
Wouldn't most of the recoil for heavy mortars be downwards? They also seem to have been fired mostly while moored to the shore, minimizing any effect at all.

jno

EDIT: I just found this, too: http://www.brownwaternavy.org/subpage/MortarRaft.htm
 
Last edited:
There's a discussion in the CWReenactors Forum:
http://www.cwreenactors.com/forum/showthread.php?11154-Mortar-Rafts
See also 'Mortar Boats' at:
http://www.cityofart.net/bship/frameset5.htm
Google Images has a lot of pics for "mortar barge", but few are really clear. Some appear to be little more than rafts with rather crude casemates. Some clearly pointed, others square, a few with tapered/blunted ends (can't remember the name for that 'trapezoidal' shape).
Also the bottom image here:
http://www.sonofthesouth.net/leefoundation/civil-war/1861/december/ft-pickens-bombardment.htm
Wouldn't most of the recoil for heavy mortars be downwards? They also seem to have been fired mostly while moored to the shore, minimizing any effect at all.

jno

EDIT: I just found this, too: http://www.brownwaternavy.org/subpage/MortarRaft.htm
A very informative article, especially the part about the reaction to firing being more lateral than perpendicular. Also, the fact that the blunt bows tended to ship water while they were being towed.
 
" The severe concussion from the firing of the morter, as described above, forced the crews to stand outside the bulwark during the firing of the piece. The sketch at left shows the positions of the crews during loading and firing. "

Ah. Yes, thank you. Still, even with the concussion downwards, boy, must have been some kind of boom when that went off. As Mark said, probably nothing special, just a plain, old boat- which somehow did not have the bottom blown out of it ( he didn't say that part, 'scuse ). I'm not even sure why I got stuck on mortar boats in the first place- think just the fascination of ' How'd they DO that ', like so many other things with engineers and the Civil War. For instance, you can see how one of those guns could be hoisted, pulled, hefted into place on land, or a RR car- must have been a ton dicier getting it onto something which floated?

Sorry, probably a big snore of a comment for folks who are conversant with this stuff- I'm still at the Holy Cow stage, this one combines engineers and ships, kinda like S'mores, marshmallows and chocolate.
 
A point of correction to an earlier post of mine; in looking at Mr. Meagher's plans this morning, I noticed that he does indicate the mortar boat had pointed ends.
 
I see. This is a mortar schooner, think I may have posted it before when first stuck on them out of curiosity- just illustrates how the force would have gone down?



civil war morter schooner 2.jpg
 
One interesting detail about mortars of that size... they weren't elevated or depressed, but permanently at a 45 degree angle. Range was adjusted by using more or less powder (propellant).

I believe both the mortar schooners and the rafts were fitted with rather solid wooden beds under the mortars... you don't want your mortar going out the bottom on the first shot. Kind of messy.
 
Gardiner's Warships of the Napoleonic Era shows plans of several bomb vessels from that period, both purpose-built and converted. The mrotars were similar, up to 13", and the accommodations for them probably didn't change much between then and the Civil War. As Mark suggested, they have heavy wooden supporting structures extending down to the keel. I expect the flexibility of wood also helped absorb the force.

Because of their sturdy construction, several bomb vessels were used in Arctic exploration in peacetime. the ship rigged bomb Carcass, in which the young Horatio Nelson served, had a full-load drat of 10' 6".
 
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